The invention relates to a rotary assistance mechanism adapted to be coupled to a driven member capable of alternately rotating in two directions in response to the rotation of a drive shaft. This mechanism comprises a motor, means for reducing the speed of the motor and at least one clutch actuated by control means. The control means includes a part, coaxial with the driven member, which slides against a resilient return means in relation to the amplitude and the direction of the drive torque.
The invention relates more particularly to the use of such rotary assistance mechanism for motor vehicle steering.
The aim of the invention is to make rotary assistance mechanisms of the kind in question more responsive and to make their working conditions less severe.